number_game.md

Help the docs!

So! The new tutorial will be focused on building several small projects in Rust. This example is the first one: a classic 'guessing game.' This was one of the first programs I wrote when I first learned C. 😄

I'd like the feedback of the community before I actually start writing the guide. So this code will be the final code of the first real example Rust programmers see. So I want it to be good. I don't claim this code is good, I just worked something out real quick.

The idea is that I will slowly build from hello world to this final code in steps, introducing one concept at a time. Here are the concepts I'd like a Rust programmer to understand by the time they're done:

Concepts

• If
• Functions
  • return (wrt semicolons)
• comments
• Testing
• attributes
• stability markers
• Crates and Modules
• visibility
• Compound Data Types
• Tuples
• Structs
• Enums
• Match
• Looping
• for
• while
• loop
• break/continue
• iterators

number_game.rs

extern crate rand;

// maybe show off that you can put multiple things in a use statement
use std::io::{BufferedReader, stdin};

use rand::Rng;

fn main() {
    println!("Guess the number!");

    let secret_number = generate_secret_number();
    //println!("Secret number is {}", secret_number);

    let mut guesses: int = 0;
    let mut reader = BufferedReader::new(stdin());

    loop {
        println!("Please guess a number from 1 to 100 (guess #{})", guesses + 1);

        let input = reader.read_line().unwrap();
        let input_num = from_str::<int>(input.as_slice().trim_right());

        let num = match input_num  {
            Some(num) => num,
            None      => continue, //maybe consider adding an error handling println!("You didn't type an int"); or something
        };

        println!("You guessed: {}", num);
        guesses += 1;

        match num.cmp(&secret_number) {
            Less    => println!("Too small!"),
            Greater => println!("Too big!"),
            Equal   => { println!("You win!"); break; },
        }
    }

    println!("You took {} guesses!", guesses);
}

// usually when I say "Guess a number from 1 to 100" we include 100, so we can show off that the max range is exclusive in Rust
fn generate_secret_number() -> int { std::rng::task_rng().gen_range(1i, 101) }